Time paradoxes
 

Let's just assume for the moment, before we all start arguing if time travel is/will be possible that time travel IS possible. Ok, I'll use the example I used the last time I had this topic.

You are sitting on the counch, eating whatever you usually eat, when suddenly the power is vut. A robber breaks in through the window, and sneaks up behind you. He puts a gun to your head, and is about to kill you. Just then a rock flies through the window, hitting the robber on the head, and incapacitating him. When you call the police, you feel a strange sensation, and when you blink, you are in front of your house ten minutes ago. You then see the power go off, and, realizing something, grab a rock and throw it through the window just as the robber from before puts a gun to yourself. When you see yourself disappear, you quickly take yourself's place.

The question is, if you had gone back in time, would the rock had still hit the robber? Or would you be dead?

What do you guys think of time travel and/or time paradoxes?

It's a fun idea to play around with, but time travel will never happen because:
1) Laws of physics screw up the whole idea.
2) Why hasn't anyone ever come back to visit us?
3) This would require religious reasons and I'm quite aware that no one wants to know.

It would screw up life as we know it. It would be like Aliens landed on Earth.

Like Harry Potter 3. Anyway, I would think you wouldn't be dead. If you went back in time the first time, and...no...wait...I would be dead!

You never know, someone might have come back in time. Just because someone hasn't said, "Hello, I'm from the future." doesn't mean they're not there :).

Also, they can't come back to the past and change the future as the past has already happened. Whatever they do (because it's already happened) is already a part of the future.

...If that makes sense...

Ya know...
If I could go back in time, I'd be a lot more happier than today...:fuzemb:

I don't want to talk about time travel. It's WAY to complecated and it's a subject I don't think scientists should get into >_>.

good god, my cousin needs to post here, if he was a member

Simply put, there is a problem with this picture. First of all, you would have to be dead because in the future you goes into the past to throw the rock. Therfore, you would be dead, and the time parodox would never happen. Second of all, how is this a time paradox? A time paradox is a thing that would interfere other things in the trail of time and this isn't one. There is a resoulation. Thrid of all, is someone else throwing the rock when the rock is thorwen in the orginal past? And what about the possiblities? There would be a time paradox if this rock is throwen before the robber came, the reaction would either be, that past self looks where the rock is thrown, and the robber comes and kills you or somthing else. You could also be knocked out of the thrown and the robber comes, doesn't kill you, and the sequence of events is destoried for never calling the police. That's my thought.

I said that you take your own place when you see yourself disappear into the past.

This is a very easy topic to hurt your head with. :D

It depends on what crackpot theory you believe.

I'm fond of the "if you change the past, then it splits off into an alternate universe" load of bull shit theory.

Oh man...I love talking about time theories and qauntum physics...

Here's more info on alternate reality theory:

Erwin Schrödinger, a German physicist who won the Nobel Prize in 1933, presented alternate reality theory. It was in 1935 that Schrödinger published one of his most famous papers, Schrödinger’s Cat Paradox…now widely known to those in the field of Quantum Physics as “Schrödinger's Cat.” The imaginary situation he proposed was this…
A cat is placed in a sealed box. Attached to the box is an apparatus containing a radioactive nucleus and a canister of poison gas. The experiment is set up so that there is a 50% chance of the nucleus decaying in one hour. If the nucleus decays, it will emit a particle that triggers the apparatus, which opens the canister and kills the cat. If it does not do this within the hour, the cat lives. So here we have a situation where the cat has a 50/50 chance of living. However, since the cat, the device, and the radioactive material are hidden under the box, nobody outside can tell whether the device has been activated yet. This leads the scientist to ponder the following: if you can't see that the cat is dead, does that mean it's still alive? Likewise, if you can't see that it's alive, does that mean it's dead? This scientist is preoccupied with a theory that two parallel universes exist inside the box at the same time: one where the cat is still alive, and another where the cat has been killed. And both of those universes will continue to exist until he lifts up a corner of the box to find out for sure.

This theory has since grown into what happens when you make a choice, and how that makes alternate realities. For instance…right now I’m writing this, but since I made a choice to write this, another reality split off where I’m not on OWF. Considering we make so many choices throughout our day, it’s hard to comprehend how many realities exist…in theory.

-oddguy

If that's it, then I'm supposing someone else has thrown the rock. But that means there is still an alternet choice of someone using a different rock to save you with. Or you just die. Or you choose to call the police the second the robber comes in the house.

But then there is a time paradox. Since you've disturbed the balance of you going back into past, confusion shall pur.

The scary thing about time is this.

If someone or something speeded up time or slowed it down or screwed it up. You won't notice. Right now as I am typing this someone might be screwing around with time (Probably not but whatever). It's just plain creepy O.o....

Schrodinger's cat pisses me off. The cat is either dead or it is alive. Just because you can't see which, it doesn't mean that both states exist.

Assuming that universes do divide along some axis of probability, then after one hour the universe would have split into two equal subsets - those where the cat survives and those where it doesn't, but still the role of the observer is utterly unclear to me.

What I beleive is, everything you do is repeated again every millisecond in time. Personally, I think ''going back in time'' is basically switching Dimensions to another the exact same, but merely back in time, hence the whole ''Lightspeed'' thing about Time. Knowing our insane geniuses in this Dimension though, we'll probably see Time Travel this millenium.

My views are actually very simialr to CS's here. I think that every second that goes by, occurs milisecodns later in another reality, and so on and so on, so that say, as you read this word, a milisecond later the you in another dimension reads it, hten another you in another dimension reads it a milisecond after that and so on and so on. It also works forwards, so after you read this word, you have already read it in another reality, which could explain foretelling hte future- a slight thinning or gap in the border between realities opens up future events to the person in contct with the gap. Unlikely but possible. I believe time travel works similarly-travelling past ligh speed creates a rip between two dimensions that are identical except for the progression on the timeline, and the rip is a way between but only sustainable while you travel past lightspeed. Therefore I think it is very hard, if not impossible, to control which time period you go to unless a variety of 'rips' occur ad you can consciously guide yourself down one. Again this is delving into the realms of the supernatural and sci-fi, but it could be true, you never know what might be happening in this world.

I want the Back to the Future style.

You can't see yourself or do anything that would **** up time, but you can travel through it in a snazzy car.

And this story can explain Mitsurs story.

Lets call the current "you" "n" (basic math). Now, when you find youself in the position of being able to throw the rock, you basically save the "you", version n+1. And then, when n+1 is "transferred" to the past (where he can save n+2), you take his place. Just like n-1 has thrown the rock for you, and has taken your place. And this goes on from "n-infinite" to "n+infinite".
In tgheory, you would be transferred to a "next" dimension.

But then again. What happens when you DON'T throw the rock? YOu would still be there, but the other you wouldn't. Would that destroy the rest of the dimensions? And thus leaving only the dimensions "n-infinite"-"n+1"?

Actually, we can see back in time. The sunlight that reaches the Earth is 8.5 minutes old. So, basically, you're watching to the suns past...

My brain hurts. I hate that cat how the heck can there be 2 dimensions in one box. If so would there not be 2 cats in the box?

When dealing with things like this, I go by what little logic and physics I know... and ignore the people who constantly shout "Well, IT'LL NEVER HAPPEN. Time travel is impossible. I'm so damn close-minded I can't think beyond what I've heard" (I really dislike those people... but I've only seen one of them and he's on Zenhex)


Anyway.

This "loop" has no forced start (i.e. someone didn't tell you to stop yourself from being killed, which then wouldn't happen so they couldn't tell you), so I'd say that if, for some reason, you spontaniously traveled back in time a few minutes and through space a relative short distance... there's nothing to stop you throwing the rock. And I don't see any reason for a person to not be in two different places at the same time (since the two of you won't be in the same space-time).

I agree with what Adder says, and what AlphaScrab says, that's pretty much what I believe happens if you can get the conundrum Mitsur suggested. And adding on what AS said about seeing the sun's past, the same holds true with the stars. Some of them will have burnt up by now, but they're so far away some of the light they gave off is only reaching our planet now, so you're seeing light/stars from thousands or maybe millinos of years ago. Therefore there are probably newer stars which we can't yet see, as their light hasn't traveled across the vast distances of space to our planet yet.

Yes. This was all summed up by Einstein with "Time is relative {to velocity and location}"... although ultimitly everything is relative.

The ability to "travel" forward through time exists. All you need to do is move very quickly. This means time passes slower relative to you, so you get to the future in less time (or, "the faster you hurry, the later you arrive {from everyone else's perspective}"). Traveling backwards in time has been dubbed "impossible"... but you never know.

O yEaH? WeLl WhIcH cAmE fIrSt, tHe ChIcKeN oR tHe EgG? HoWs ThAt FoR a TiMe PaRaDoX?

Wired, could you please referain youself to use BrEeZaH-linguo? You'll be better liked then. And that's what we all want, no?

As for your q. The chicken evolved from dinosaurs, which in turn evolved from micro-organisms. Which could multiply themselves.

First came the single celled organism. Then came sexual reproduction.

The 'time is related to velocity' thing, isn't that the theory Einstein had that if you takec 2 identical twins who are say 20 years old, and stick one in a rocket and send her into space for several Earth years (Lets say 40), then when she returns to Earth, the twin who stayed on earth will be 60 yet the one wh owent in the rocket will only be in like her 30's-40's? 9I actually have this written down somewhere in a book on space, I'll try and find it.)
EDIT: Here it is, straight from the book:
'At the start, the twins are aged 25. Both are living on Earth, and time passes at the same rate for each of them.
One twin gets on the spacecraft, and it speeds off from Earth at 98% lightspeed. After 5 years on the ship's onboard clock, the twin turns it round and heds back to earth.
When the astronaut twi nreturns, she is 35 (5 years each way) but the twin who stayed on earth is 70. This is because time passes slower the faster the object moves. That the theory you meant?


And can you explain the 2nd bit again, I get the 'travelling faster reduces relative time' bit, but this 'faster you travel, later you arrive' confuses me. Do you mean that it only appears that you are travelling faster, or something else? EDIT: Did you mean the theory of time dilation- time appears to pass slower and acts slower on somehting the faster it moves, thus creating a 'shortcut' through time?

"Time dilation" - yes.

The idea is that since the speed of light is constant through any medium (regardless of the velocity of the viewer), time must be relative.

The example:

You're in a train and you throw a rock at 5 meters/sec. Someone looking at the train go past them will see you throw a rock and the rock traveling at 5 m/s faster than the train. However, if you were to use a laser and measure the speed of light on the train you would "see" light traveling at the same velocity as someone who was stationary and looking at the laser light.
{I know that doesn't seem to make any sence, but it's aparently been proven}

So... if I move at the speed of light for one year (say, in a spaceship that keeps going back-and-forth between the moon and the earth) no time will pass relative to me {I won't get older} but time will pass as normal for the earth {everyone else will be one year older since one year has passed}.

The joke I made out of this is "don't rush or you'll be late", since the faster you move the further forward in time you get relative to everyone else {you will be earlier by your watch, but later by everyone else's}

^Ah, I understand now. Interesting stuff there.

This is where I use my theory of "Time doesn't break or reach infinite loops"

Either 1.) You can't NOT throw the rock. It breaks time

or 2.) By not throwing the rock, you create a new time-line (new reality) where you haven't thrown it.

Now, if you didn't throw it you would have died which means you wouldn't have been there to throw it... which would work since you never would have gone to the past to be able to throw it.

Since in order to get to the past to throw the rock you have to have already thrown it, it appears to be impossible not to throw the rock. If you somehow can NOT throw the rock, you need another time-line/reality to exist.

(I don't really go by the "Destroy all reality" thing)

To explain the "infinite loop" thing:

-You go back in time to kill Hitler. You've already failed.
If you hadn't of failed, you would have killed Hitler and I wouldn't be using him as an example.
If you succeded, it hasn't made any difference so you must have created a new reality. Otherwise, I wouldn't be useing him as an example.

Thinking in terms of a single time-line, if you go back in time you would have already been there and effected that time... so you're not really changing the past, you're just doing what has already been done.